From: Daren (mdaren@uswest.net)
Date: 12/11/01-05:19:44 PM Z
Sandy,
If what you have just stated is true then when shooting with my softbox
the inverse square law shouldn't apply?? That's absurd!! And what about
flourecent banks used for lighting?? Are these not effected by inverse
square law??? Something is more than a bit fishy here.
Light falls off at a regular rate regardless of relative distance and
size of light source to subject (point source vs. soft source). The
idea that a soft or broad source will create light in any way different
than a point source is wrong. Light is light, we obviously have
different wave legnths in the elctromagnetic spectrum, but a photon is
just a photon. The photon doesn't know the difference between "soft",
"hard", "bright" or "dim", it is simply a photon. Besides, the ONLY
difference between a point source and a soft source is distance from
source to subject and size relative to one another. Unless acted upon
by a great force (large amounts of gravity) or another substance (glass,
etc.) light has no "choice" but to obey the laws of physics, that
includes the inverse square law. Light is not magic, it can and must be
described in a rational way.
Sandy King wrote:
> Robert,
>
> The inverse square law only applies to point source lights. I knowfrom
> experience that it does not apply to banks of fluorescent tubes when
> used at typical exposing distances of 2-6".
>
> I can not give you the math or optical laws for this, however, there
> was a thread on this subject on the list some time ago, perhaps a year
> or more? At this point I don't know how to search the archives and
> hope that perhaps someone else can direct you to the thread.
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